I've seen the youtube videos from those removing the cowl. I haven't tried it, so can't really judge it. I have done two plug changes on our ES350 Lexus (same as Camry) and it is fairly straight forward. The first time, I didn't replace the plenum gaskets, but I did on the 2nd plug change. Now, if you have small arms and hands, there some DIY'ers who have replaced the rear plugs without removing the plenum or the cowl. I tried and could not contort myself into position to do that. Removing the plenum does provide the opportunity to clean the throttle plate, which I am certain will need some cleaning